Temporal Variance of Typhoon Disasters in Recent Six Centuries in Shanghai and Preventing ,Mitigating Strategies

(Shanghai Typhoon Institute/China Meteorological Administration , 166 Puxi Road, Shanghai,China,200030)

Abstract: Typhoon disasters make crucial influences on tropical and subtropical coastal area.Severe typhoon disasters endanger public safety of coastal metropolises security, district and even national security, not only cause people casualties and economic losses, but also make negative influences on social psychology and stability, result in ecosystem decay, consequently impede the sustainable social and economic development. From 1950 to 2000, Shanghai encountered about 50 typhoon-inducing disasters, among which no.4906 typhoon, no.6214 typhoon, no.6312 typhoon, no.7413 typhoon, no.8114 typhoon , no.9711 typhoon and no.0509 typhoon all brought grave negative influences. Based on reconstructed historical data in the last six centuries, this paper summarized the number of extreme events of typhoon disasters in Shanghai since 1400. It is discovered that nearly 300 typhoon disasters happened in Shanghai from 1400 to 2000, among which 17 typhoon disasters made tragic consequences with over 10 thousands people dead. The most destructive typhoon happened in 1696. Three features should be emphasized. Firstly, the frequency of typhoon disasters presents an increasing trend in the six hundred years. The frequency is less than 5 during every 10 years before 1560, while it is far larger than 5 in most of 10-year periods after 1780. Secondly, the fluctuant character of temporal change of typhoon disasters in Shanghai is evident. In some periods, there were many typhoon disasters, while there were quite few in some others. In the period of most frequent typhoon attacks, 16 typhoon disasters occurred in ten years. The recent ten years encountered less typhoon disasters than normal. The two longest periods above the frequency of normal typhoon disasters are from 1561 to 1590 and from 1911 to 1940. The longest period below the frequency of normal typhoon disasters is from 1721 to 1780. Thirdly, July to September is the peak time of typhoon disasters around the year. The highest frequency of typhoon disasters in Shanghai is in August 21-31. It was pointed out that there are the fluctuation cycles of 2.5 ,3,9.8,21.3,32.1 and 43.9years,and there will be a rising trend of typhoon disaster in the next decade.In addition,potential risks of typhoon disasters are increasing with the rapid urbanization , global warming and sea level rising. Other hidden trouble will become complex.All of these will threaten the safety of Shanghai. It is urgent to strengthen the researches on impacts of typhoon disaster on city's safety and establish and perfect the city's disaster prevention, resisting and mitigating strategy.Finally, it is conceived to apply modern engineering achievements,to establish a modern and high standard decision-making system.to prevent and mitigate typhoon disaster for coastal population centers at low elevations like Shanghai and other spots around coastal regions.

Keywords: Typhoon Disaster, Temporal Variance , Disaster prevention and Mitigation